During the tibial tuberosity advancement procedures in canines, the tibia is cut just behind the tibial tuberosity and the tibial tuberosity is advanced to achieve a perpendicular relationship between the tibial plateau slope and the patella tendon. A titanium or stainless steel implant (also called a cage or spacer) is placed between the advanced tibial tuberosity and the tibia and a plate is used to secure the tibial tuberosity to the tibia.
Over time, bony growth forms in and around the spacer. In the case of an infection or other problem, it can be very difficult to remove the spacer. As many as one in ten tibial tuberosity advancement procedures result in infection or rejection of the spacer implant.
Biocompatible and biodegradable materials are known for use in implants but an implant made of a plastic biodegradable material and designed like prior art metal implants may not be strong enough to maintain the tibial tuberosity in the advanced state as the canine recovers and becomes active. Injection molding limitations also prevent manufacturing a plastic implant designed like the prior art metal tibial tuberosity implant.